I've heard terrible things about Al Maha. It's apparently a lounge to avoid even if you get free access. If you're looking for a snooze I remember that they have these sleep pod things that you may be able to pay for.

I recall being able to purchase lounge access on an economy ticket to the vastly superior Al Mourjan lounge - think it was around 99 USD. Is this option offered to you?

If you're on a tight budget and don't mind exploring, DOH is a massive airport and you can definitely get your steps in. There is also a garden there that you can check out, there's also plenty of places to plug in and charge your phone. It is probably one of the airports I don't mind not having lounge access in. You will find somewhere calm...